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During summer, a portable air conditioner becomes a necessity for most of us. A portable AC is ideal for an off grid system since it consumes less power than a central AC. But what inverter size will you need and how long can you run it?
A 2500W inverter can power a 5000 BTU portable air conditioner running at 1.5kwh. With a 600ah 12V battery bank, the air conditioner can run for 4 to 5 hours.
Inverter Size Guide For Portable Air Conditioner
If you want the answer right away, here is a guide to the most common portable air conditioners= sizes. These figures are based on the normal settings, so if you set it to high the power consumption will go up.
|AC BTU Size||Power Consumption||Recommended Inverter Size|
A word here about pure sine and modified sine wave inverters. There are some good modified sine wave inverters, but for an AC, pure sine is more suitable.
If you have a 5000 BTU AC, the Renogy 12V 2000W Pure Sine Wave Inverter is going to have no problems running it. Using the table above you can get an idea what inverter size works best for which AC.
Pure sine wave inverters allow current to flow into appliances as if they are running on regular power. It is smoother, cleaner and more efficient. More importantly, pure sine wave are meant to be used with powerful appliances like air conditioners and refrigerators.
So we recommend using a pure sine wave inverter. You will probably use other appliances with the AC, and it makes sense to install a high quality inverter to do the job.
Some more reminders:
- Use this guide as reference only. Check the specs on your air conditioner for more details.
- Modern air conditioners use much less power than older units.
- Modern portable AC systems need less startup power than older models.
- You have to get an energy efficient AC if you want to use one in an off grid solar system.
- You can also use this guide if you want to run air conditioners off solar panels
- These portable air conditioner figures assume the models are Energy Star compliant.
- The inverter size assumes there are no other loads. You will need a larger inverter if you are going to use it with other appliances.
- The inverter size given here is the ideal. Modern portable AC systems consume less startup power than older models. But it is still better to have a good sized inverter.
How Much Power Does a Portable Air Conditioner Use?
The table above gives you an idea what inverter size you need. Portable AC watts per = minimum inverter size required. But there is more to it than that. To get the best results you have to understand BTUs and watts.
Air conditioners are measured in BTU (British Thermal Unit). 1 BTU an hour = .29 watts.
An 8000 BTU portable AC consumes 2320 watts an hour. This is an estimate only. Large AC systems use more power, and even a portable AC will consume more watts if the highest settings are used.
But let’s assume the AC uses 2320 watts. In this case you need a minimum 2500W inverter to run an 8000 BTU portable AC.
Air conditioners need more power to start up, but that will not be an issue. 2500W inverters usually have a 5000W peak capacity, more than enough for modern AC units.
This calculation assumes the inverter is only going to load the AC. You will need a larger inverter to run a coffee maker refrigerator or other appliances.
An example: your portable AC consumes 1500 watts an hour. You have a 200W inverter so there is enough power available.
But what happens if you run more appliances? If you add a 200W laptop, 100W lights, a modem and speakers, the load will be close to 2500 watts, if not more.
The number one rule with solar components (solar panels, batteries, inverters and charge controllers) is to never run them at full power. Always have some reserve.
When you calculate inverter sizes for an air conditioner, keep the other appliances in mind. If you want to run several appliances, add the watts of every appliance, including the air conditioner.
How Long Can an Inverter Run a Portable Air Conditioner?
Now that you have a portable air conditioner running, how long can you use it? The answer depends on the power source.
Obviously if you are running the AC from 110V or 120V, it just keeps going unless there is a power outage. With a battery bank or generator, you have to do some math.
You have an 8000 BTU portable AC with power consumption at 2500 watts an hour. Your inverter has a 3000W capacity.
How many batteries will you need to run the AC for 5 hours?
Multiply AC watts per hour by the running time. Divide the watts by battery voltage and the result is the number of battery amps required.
Start by deciding what battery voltage to use, 12V or 24V. Let us use 12V as an example.
2500W / 12 = 208.3
So you need 208.3 amps to run a 2500W AC for an hour. To keep it going for 5 hours would require 1040 amps.
There is no 208.3ah battery and the closest widely available size is 250ah.
250ah x 5 = 1250ah
A battery bank consisting of 5 x 250ah batteries gives you 1250ah, more than enough to run an 8000 BTU portable air conditioner. Or you can use five 300ah Ampere Time Lithium Batteries for even longer running time.
More about Portable AC Runtime
If you are going to use lead acid batteries to power the air conditioner, consider doubling the battery capacity. If your calculations show 1040 amps are needed, get a 2080 amp battery bank.
Lead acid batteries are designed to run only at 50% capacity. You can empty the battery, but it will cause the circuits to deteriorate. This will not happen overnight but it is going to reduce the battery life cycle.
You can also use lithium batteries instead for a longer discharge rate. They do cost more so that is the tradeoff. But even lithium batteries are usually not fully discharged, only at 85% or so.
Check the battery instructions on the proper discharge rate to use. Just like with the inverter, the battery size we gave here is for the AC only. You will need a bigger battery bank or another power source to load more appliances.
In other words you need more than just an inverter to run a portable AC. If you are on the grid, no worries as the system is running on electricity. Or if you are on solar, you can switch to AC anytime.
But if you are off grid, you have to count the amps, watts and volts. Fortunately the calculations are straightforward so there are no issues here.
What Portable Air Conditioner Size Do I Need?
The rule of thumb is an AC requires 20 BTU per square feet. Floor space is measured by multiplying the floor width and length.
- 300 sq. ft. or less – 10000 BTU or less
- 500 sq. ft. – 10000-15000 BTU
- More than 500 sq. ft. – more than 15000 BTU
This is a very simplified guide. If you are in an RV or mobile home, a smaller AC will be sufficient.
Other factors to consider are the ceiling height, how much sun gets in, the shape of the room etc. Here are some tips.
- Increase the BTU if you are going to install the air conditioner in the kitchen or another warm area. The
- more sunlight or heat goes into a room, the more AC power is needed.
- More people requires more BTU power. Some suggest adding 500 BTU more, but it depends on preference and prevailing temperature.
- If the area is shaded you can lower the BTU power by 15% or so. Adjust the settings until you are satisfied.
- Higher ceilings usually require more AC cooling power.
- It ultimately comes down to personal preference. You decide what BTU AC size works best for you and what fits with your system.
- Potable AC units have different settings and options . The adjustments you make have a direct impact on how much power is going to be consumed.
There are a lot of factors to consider, but yes you can run a portable AC on an inverter. All it takes is planning and making sure that you have enough battery power to run the AC as long as you need.
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